The below list of 20 Top AIX Interview Questions and Answers for freshers and experienced pdf
1. What levels of AIX have you worked with?
Answer:
=> AIX 4.3.3 and AIX 5.1 good
=> If only AIX 4.2.1, 4.1, or 3.2, bad
2. What types of machines have you worked with?
Answer: Look for questions pertaining to the hardware, to ascertain level of competence and understanding.
Take note of applicants who mention older technologies like “SP2” or newer technologies like “Regatta”
3. What applications have you used with AIX?
Answer: Look for applications like HACMP, ADSM/TSM, SAP, i2, Manugistics, MQ Series, WebSphere, etc.
An applicant with considerable HACMP experience is likely to have quite a bit of AIX knowledge, especially LVM, disks, general TCPIP, and application enablement.
4. Suppose that there are some users that need to run certain commands normally only accessible by root. How would you grant them access?
Answer: sudo
Question: Discuss your philosophy on granting user access to root or to an application user ID.
Answer: For root, prefer to
5. The system is performing very slowly; you have discovered that this is due to an increasing number of defunct processes are being created. How can you determine the cause?
Answer:
1. Check to see if new defunct processes are being created, owned by the init process, with no processes being deleted at all.
2. If some defunct processes are being cleared out and the overall number of defunct processes is still growing, then this is due to an application creating more defunct processes than the init process can clean out.
3. However, if NO defunct processes owned by init (PID 1) are being cleared out, this points to an incorrect wait entry in the /etc/inittab file. The init process is stuck on this wait entry and will not cycle through the defunct processes until that entry finishes. The solution is to change that “wait” entry to a “once” entry.
6. You get a message that the system can’t fork any additional processes? What do suspect to be the problem?
Answer: Either paging space is full or maxuproc (maximum number of user processes) is set too low.
7. You’re running some commands and getting an error that says “srcmstr daemon is not running”. Obviously, it is, because the machine appears to be functional. What is the likely cause?
Answer: Someone has updated some of the base kernel filesets without rebooting the machine.
8. How do you run 64-bit applications on AIX 4.3.3? On AIX 5.1? What else might you have to consider on an AIX 5 machine?
Answer:
=> AIX 4.3.3 only comes with a 32-bit kernel, so you need to ensure that 64-bit application support is enabled (via the load64bit entry in /etc/inittab or done via SMIT).
=> For AIX 5.1, either use the same method as AIX 4.3.3 OR configure the system to use a true 64-bit kernel. If you use a true 64-bit kernel, any 32-bit application will NOT run.
ODM
9. Describe one situation where it might be appropriate to edit the ODM.
Answer: E.g., need to make parameter changes to a device that is open, and that cannot be modified without closing the device (i.e., a network device), and where the machine can be easily rebooted following the change.
10. Describe how to manually edit the ODM. What commands should be used?
Answer:
1. Use the odmget command to grab the appropriate entries from the ODM, into a text file.
2. Edit these entries.
3. Use the odmdelete command to delete the current entries.
4. Use the odmadd command to add the new entries.
5. If these are device configuration files, use the savebase command to save them into the boot image.
11. When might the savebase command be used?
Answer: After making manual changes to the CuAt, CuDv, CuDvDr, CuDep, or CuVPD ODM classes (aka the device configuration database), these classes must be saved into the boot image in the boot logical volume. If they are not saved, there is a risk run that the changes won’t be saved at boot. Note that the chdev command (and others) will cause savebase to be run.
12. What key would you use at boot time to signal the machine to boot into service mode?
Answer: F5 or 5 will signal the machine to boot from the internal boot list. F1 or 1 will bring the machine into SMS mode. The F[x] keys are used for graphical consoles; the others are used on ASCII consoles.
13. What is the effect of setting the normal mode bootlist to cd0 first and hdisk0 second?
Answer: The machine will boot from the CDROM into maintenance mode automatically if a boot CD has been inserted. If not, the machine will boot from the disk into normal mode.
14. A machine hangs at boot because the network is inaccessible or an NIS server is accessible. How can you recover?
Answer: With inaccessible network (LED 581 for a long time), the machine will generally recover after timing out. With a NIS problem, probably have to boot into service mode
15. You are adding a number of new internal SCSI disks to a pSeries 680 and a new drawer of SSA drives. How does cfgmgr operate different when configuring each?
Answer: Internal SCSI drives are discovered one at a time by order of their SCSI ID (i.e., their slot location). SSA drives are discovered by their SSA serial number, which has nothing to do with their slot in the drawer.
16. After a reboot or after running cfgmgr, a particular disk is listed twice. Give some possible reasons why and how you might narrow them down.
Answer:
1. The disk can be detected, but it has failed and since cfgmgr can’t verify the physical volume identifer, it marks the old disk Defined and then creates a new disk entry with no PVID.
2. You are running in a multi-path (either SAN or twintailed SCSI) environment and the system is (properly) seeing the disk multiple times.
=> If one disk is Defined and the other Available, or lspv shows the second instance as having no PVID, then it’s probably #1. Also check the error report.
=> If the disk is seen as being Available twice (and lspv lists it twice), it’s probably #2.
17. What considerations must you give when creating RAID-0 or RAID-1 disks in an SSA array?
Answer: You cannot cable RAID-0 or RAID-1 arrays such that there are multiple adapters in the loop (as opposed to RAID-5).
18. What’s the difference between RAID-0 and RAID-1?
Answer: RAID-0 is hardware striping. RAID-1 is mirroring.
19. When using an SSA array, what are the tradeoffs to consider between using a large RAID-5 array and using LVM mirroring?
Answer: RAID-5 would waste fewer disks, but it would be slower.
20. How do you properly mirror rootvg to protect the OS from crashing should a disk fail?
Answer:
1. Use the mirrorvg command to mirror the logical volumes
2. Run the bosboot command to reboot the boot image and update the disk boot record on both disks that contain a copy of the boot logical volume.
3. Run the bootlist command to add both disks to the boot list.
4. Mirror all non-rootvg paging spaces as well as those in rootvg.
1. What levels of AIX have you worked with?
Answer:
=> AIX 4.3.3 and AIX 5.1 good
=> If only AIX 4.2.1, 4.1, or 3.2, bad
2. What types of machines have you worked with?
Answer: Look for questions pertaining to the hardware, to ascertain level of competence and understanding.
Take note of applicants who mention older technologies like “SP2” or newer technologies like “Regatta”
3. What applications have you used with AIX?
Answer: Look for applications like HACMP, ADSM/TSM, SAP, i2, Manugistics, MQ Series, WebSphere, etc.
An applicant with considerable HACMP experience is likely to have quite a bit of AIX knowledge, especially LVM, disks, general TCPIP, and application enablement.
4. Suppose that there are some users that need to run certain commands normally only accessible by root. How would you grant them access?
Answer: sudo
Question: Discuss your philosophy on granting user access to root or to an application user ID.
Answer: For root, prefer to
5. The system is performing very slowly; you have discovered that this is due to an increasing number of defunct processes are being created. How can you determine the cause?
Answer:
1. Check to see if new defunct processes are being created, owned by the init process, with no processes being deleted at all.
2. If some defunct processes are being cleared out and the overall number of defunct processes is still growing, then this is due to an application creating more defunct processes than the init process can clean out.
3. However, if NO defunct processes owned by init (PID 1) are being cleared out, this points to an incorrect wait entry in the /etc/inittab file. The init process is stuck on this wait entry and will not cycle through the defunct processes until that entry finishes. The solution is to change that “wait” entry to a “once” entry.
6. You get a message that the system can’t fork any additional processes? What do suspect to be the problem?
Answer: Either paging space is full or maxuproc (maximum number of user processes) is set too low.
7. You’re running some commands and getting an error that says “srcmstr daemon is not running”. Obviously, it is, because the machine appears to be functional. What is the likely cause?
Answer: Someone has updated some of the base kernel filesets without rebooting the machine.
8. How do you run 64-bit applications on AIX 4.3.3? On AIX 5.1? What else might you have to consider on an AIX 5 machine?
Answer:
=> AIX 4.3.3 only comes with a 32-bit kernel, so you need to ensure that 64-bit application support is enabled (via the load64bit entry in /etc/inittab or done via SMIT).
=> For AIX 5.1, either use the same method as AIX 4.3.3 OR configure the system to use a true 64-bit kernel. If you use a true 64-bit kernel, any 32-bit application will NOT run.
ODM
9. Describe one situation where it might be appropriate to edit the ODM.
Answer: E.g., need to make parameter changes to a device that is open, and that cannot be modified without closing the device (i.e., a network device), and where the machine can be easily rebooted following the change.
10. Describe how to manually edit the ODM. What commands should be used?
Answer:
1. Use the odmget command to grab the appropriate entries from the ODM, into a text file.
2. Edit these entries.
3. Use the odmdelete command to delete the current entries.
4. Use the odmadd command to add the new entries.
5. If these are device configuration files, use the savebase command to save them into the boot image.
11. When might the savebase command be used?
Answer: After making manual changes to the CuAt, CuDv, CuDvDr, CuDep, or CuVPD ODM classes (aka the device configuration database), these classes must be saved into the boot image in the boot logical volume. If they are not saved, there is a risk run that the changes won’t be saved at boot. Note that the chdev command (and others) will cause savebase to be run.
12. What key would you use at boot time to signal the machine to boot into service mode?
Answer: F5 or 5 will signal the machine to boot from the internal boot list. F1 or 1 will bring the machine into SMS mode. The F[x] keys are used for graphical consoles; the others are used on ASCII consoles.
13. What is the effect of setting the normal mode bootlist to cd0 first and hdisk0 second?
Answer: The machine will boot from the CDROM into maintenance mode automatically if a boot CD has been inserted. If not, the machine will boot from the disk into normal mode.
14. A machine hangs at boot because the network is inaccessible or an NIS server is accessible. How can you recover?
Answer: With inaccessible network (LED 581 for a long time), the machine will generally recover after timing out. With a NIS problem, probably have to boot into service mode
15. You are adding a number of new internal SCSI disks to a pSeries 680 and a new drawer of SSA drives. How does cfgmgr operate different when configuring each?
Answer: Internal SCSI drives are discovered one at a time by order of their SCSI ID (i.e., their slot location). SSA drives are discovered by their SSA serial number, which has nothing to do with their slot in the drawer.
16. After a reboot or after running cfgmgr, a particular disk is listed twice. Give some possible reasons why and how you might narrow them down.
Answer:
1. The disk can be detected, but it has failed and since cfgmgr can’t verify the physical volume identifer, it marks the old disk Defined and then creates a new disk entry with no PVID.
2. You are running in a multi-path (either SAN or twintailed SCSI) environment and the system is (properly) seeing the disk multiple times.
=> If one disk is Defined and the other Available, or lspv shows the second instance as having no PVID, then it’s probably #1. Also check the error report.
=> If the disk is seen as being Available twice (and lspv lists it twice), it’s probably #2.
17. What considerations must you give when creating RAID-0 or RAID-1 disks in an SSA array?
Answer: You cannot cable RAID-0 or RAID-1 arrays such that there are multiple adapters in the loop (as opposed to RAID-5).
18. What’s the difference between RAID-0 and RAID-1?
Answer: RAID-0 is hardware striping. RAID-1 is mirroring.
19. When using an SSA array, what are the tradeoffs to consider between using a large RAID-5 array and using LVM mirroring?
Answer: RAID-5 would waste fewer disks, but it would be slower.
20. How do you properly mirror rootvg to protect the OS from crashing should a disk fail?
Answer:
1. Use the mirrorvg command to mirror the logical volumes
2. Run the bosboot command to reboot the boot image and update the disk boot record on both disks that contain a copy of the boot logical volume.
3. Run the bootlist command to add both disks to the boot list.
4. Mirror all non-rootvg paging spaces as well as those in rootvg.
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